The objective of this study is to clarify the role of membrane glycoproteins in the regulation of growth of normal and tumorogenic transformed cells. Our approach is a two-fold plan. First to isolate and characterize selected glycoproteins from normal and transformed cells. This aspect will include: (a) Isolation by affinity chromatography of membrane glycoproteins specifically reactive with Conconavalin A and Wheat Germ Agglutinin, (b) Comparison by physical and chemical methods of these glycoproteins among themselves and with those obtained from normal and transformed cells, and (c) To prepare specific antibodies to each of the glycoproteins and to compare their immunologic relationship and specificity. The second aspect relates to studies on the biologic role of the membrane glycoproteins and will include: (a) Studies on the effect on growth control of specific monovalent antibodies added to the medium of transformed cells, and (b) The effect of added specific monovalent antibodies on cellular c-AMP levels.